Foldable elliptical fitness machine

ABSTRACT

A foldable elliptical fitness machine comprises a first frame securely supported on a floor and a second frame for installing an elliptical structure, and the second frame is pivotally coupled to the first frame by a pivoting device, such that the second frame can be rotated with respect to the first frame, wherein the elliptical structure comprises a rotating member having two eccentric pivotal points, and two pedal arms. A central penetrating axle of the rotating member is pivotally coupled onto the second frame, and each eccentric pivotal point is pivotally coupled to the first end of the pedal arm, and each pedal arm includes a footrest for a user to step. If the first end of the pedal arm rotates with the crank, the footrest will move in an elliptic path. With the foregoing structural design, the elliptical structure can be fully folded to improve the convenience of use.

FIELD OF THE INVENTION

The present invention relates to a foldable elliptical fitness machine,and more particularly to an elliptical fitness machine structure thatincludes a first frame and a second frame, and wherein the second frameinstalled an elliptical mechanism, and the second frame can be turnedand folded upright with respect to the first frame and supportedsecurely by the first frame to achieve the purposes of effectivelyfolding and using the elliptical fitness machine.

BACKGROUND OF THE INVENTION

In general, the basic structure of a prior art elliptical fitnessmachine includes a flywheel, two cranks, and two pedal arms, and a firstend of each crank is coaxially connected to the flywheel, and a secondend of each crank is pivotally connected to a first end of eachcorresponding pedal arm, and each pedal arm has a footrest, such that auser can step on the footrest. If the first end of the pedal arm rotateswith the crank, the footrest will move in an elliptic path.

Since the elliptical fitness machine provides the function of a stridingexercise, the elliptical fitness machine becomes one of the fitnessequipments as popular as the treadmill. If the elliptical fitnessmachine and the treadmill are placed flatly on a floor for their use,the footprint of these fitness equipments occupy much area. To reducethe footprint of the fitness machines when the machines are not in use,some treadmills are designed to have a belt that can be folded upward,and it is not easy to design a foldable elliptical fitness machinebecause many mechanisms are disposed on the link rod, and the ellipticalfitness machines are usually designed as a partial foldable structure.All of the present elliptical fitness machines do not come with astructure having a variable inclined body. For example, U.S. Pat. No.6,149,551 only disclosed a foldable elliptical exercise machine thatincludes one frame, and the frame includes the main components such as aflywheel and a crank to operate with a pedal arm and the track isdesigned to have a free end which can be turned and folded upright withrespect to a second frame. The elliptical exercise machine is partiallyfolded, and the footprint is still large after the machine is folded.Furthermore, such foldable exercise machine does not come with afunction of changing the inclination of the machine, and thus userscannot change the level of difficulty of their exercise by changing theinclination of the elliptical fitness machine. U.S. Pat. No. 6,146,313disclosed a cross training exercise device, and the end of a pedal armis connected to a guide track for adjusting the height and changing theexercise path of the pedal arm. However, the structure of this machineis not stable enough.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a fullyfoldable elliptical fitness machine to improve the convenience of itsuse, and the foldable elliptical fitness machine comprises a first frameand a second frame, wherein the first frame securely supported on afloor and the second frame installed an elliptical structure, and thesecond frame is pivotally coupled to the first frame by a pivotingdevice, such that the second frame can be rotated with respect to thefirst frame, wherein the elliptical structure comprises a rotatingmember having two eccentric pivotal points, and two pedal arms. Acentral penetrating axle of the rotating member is pivotally coupledonto the second frame, and each eccentric pivotal point of the rotatingmember is pivotally coupled to a first end of the corresponding pedalarm, and each pedal arm includes a footrest, such that a user can stepon the footrest. If the first end of the pedal arm rotates with thecrank, the footrest will move in an elliptic path. With the foregoingstructural design, the elliptical structure of the invention has thefunctions of being fully folded upright and improving the convenience ofusing the elliptical fitness machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a basic structure and a structure having asmaller inclination and a usable status according to a first preferredembodiment of the present invention:

FIG. 2 is a schematic view of a second preferred embodiment of thepresent invention;

FIG. 3 is a schematic view of a third preferred embodiment of thepresent invention;

FIG. 4 is a schematic view of a structure as depicted in FIG. 3 which isadjusted to have a larger inclination;

FIG. 5 is a schematic view of a structure as depicted in FIG. 3, whichis folded;

FIG. 6 is an exploded view of a portion of the first preferredembodiment as depicted in FIG. 1;

FIG. 7 is a schematic view of an assembled structure as depicted in FIG.6;

FIG. 8 is a schematic view of a structure as depicted in FIG. 1 whichhas a larger inclination and a usable status;

FIG. 9 is a schematic planar diagram of FIG. 1;

FIG. 10 is a schematic planar diagram of FIG. 8;

FIG. 11 is a schematic view of a partially folded structure of thepresent invention;

FIG. 12 is a schematic view of a fully folded structure of the presentinvention;

FIG. 13 is a schematic view of a fourth preferred embodiment of thepresent invention;

FIG. 14 is a schematic view of the movements with respect to FIG. 13;and

FIG. 15 is a schematic view of a second frame together with anelliptical structure being folded upright according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 3, a foldable elliptic fitness machine accordingto a preferred embodiment of the present invention comprises a firstframe 10 and a second frame 20, wherein the first frame 10 securelysupported on a floor and the second frame 20 installed an ellipticalstructure, and the second frame 20 is pivotally coupled with the firstframe 10 by a pivoting device 30, such that the second frame 20 and theelliptical structure 2 can be fully rotated and folded upright withrespect to the first frame 10, and the first frame 10 stably supportsthe second frame 20, wherein the elliptical structure 2 is like ageneral prior art structure comprising a rotating member 22 having twoeccentric pivotal point 220 a, 220 b, and two pedal arms 23 a, 23 b, anda central penetrating axle 220 of the rotating member 22 is pivotallycoupled to the second frame 20, and the two pivotal points 220 a, 220 bof the rotating member 22 are separately and pivotally coupled to thecorresponding first end of a pedal arm 23 a, 23 b, and each pedal arm 23a, 23 b includes a footrest 24 a, 24 b, such that a user can step on thefootrest 24 a, 24 b. When the first end of the pedal arm 23 a, 23 brotates with the rotating member 22, the footrest 24 a, 24 b can move inan elliptic path. With the foregoing structural design, the ellipticalstructure 2 of the invention can be folded upright to improve theconvenience of using the elliptical fitness machine. In the foregoingbasic structure, the rotating member 22 is coaxially coupled with twocranks 22 a, 22 b to form a rigid body, and the axle 220 is pivotallycoupled onto the second frame 20.

The present invention installs a pivoting device 30 for pivotallyconnecting the second frame 20 with the first frame 10 of the ellipticalstructure 2. Many preferred embodiments are feasible for the inventionand three of them as shown in FIGS. 1 to 3 are used for illustrations.The second preferred embodiment as shown in FIG. 2 can use a simplepivotal axle 300 to pass through the second frame 20 and the first frame10, such that the second frame 20 can be rotated to an angle withrespect to the first frame 10. As to an enabling assembly 4 for enablingthe second frame 20 to rotate with respect to the first frame 10, asupport rod 70 is pivotally coupled to a rear end of the second frame20, and an actuating device 71 is connected between the support rod 70and the second frame 20. The actuating device 71 includes a body 72 anda contractible rod 73, and the contractible rod 73 can be contractedwith respect to the body 72, such that the support rod 70 can be swungto an angle to support a rear end of the second frame 20 to definepositions of different heights and achieve the function of changing theinclination of the second frame 20. The third preferred embodiment asshown in FIGS. 3 to 5, a link rod 80 and a swinging rod 81 are pivotallycoupled to the same pivotal point at the front end of the second frame20, and another end of the link rod 80 is pivotally coupled to the firstframe 10, and a roller 82 is pivotally coupled to a free end of theswinging rod 81, and the first frame 10 includes a track 83, and theroller 82 of the swinging rod 81 is in contact with the track 83, andthe enabling assembly 4 has an actuating device 84 connected between thefirst frame 10 and the swinging rod 81, and the actuating device 84includes a body 85 and a contractible rod 86, and the contractible rod86 can be contracted with respect to the body 85, such that the swingingrod 81 is swung to an angle to support the front end of the second frame20 to define positions of different heights, so as to achieve thefunction of changing the inclination of the second frame 20.

Since the structure of the present invention includes a structure asillustrated by a complete set of drawings of the first preferredembodiment, therefore the following movements are illustrated by usingthe first preferred embodiment as shown in FIGS. 1, 6, and 7. Thepivoting device 30 according to the first preferred embodimentcomprises:

two side panels 11 a, 11 b, disposed on a first frame 10, and each ofthe two side panels 11 a, 11 b includes a first pivotal connectingportion 12 a, 12 b and a second pivotal connecting portion 13 a, 13 b;

two side rods 200 a, 200 b, disposed on the second frame 20, and each ofthe two side rods 200 a, 200 b includes a pivotal connecting portion 201a, 201 b proximate to a distal end;

two first link rods 31 a, 31 b, and each first link rods 31 a, 31 bincludes a first pivotal connecting portion 310 a, 310 b, a secondpivotal connecting portion 311 a, 311 b and a third pivotal connectingportion 312 a, 312 b, and the third pivotal connecting portion 312 a,312 b on each first link rod 31 a, 31 b and a pivotal connecting portion201 a, 201 b corresponding to a side rod 200 a, 200 b on the secondframe 20 are passed through a pivotal axle (not shown in the figure) forthe pivotal connection;

two second link rods 32 a, 32 b, and a first end of each second link rod32 a, 32 b is passed through a pivotal axle and pivotally coupled to afirst pivotal connecting portion 12 a, 12 b corresponding to a sidepanel 11 a, 11 b of the first frame 10, and a second end is passedthrough a pivotal axle (not shown in the figure) and pivotally coupledto a corresponding first pivotal connecting portion 310 a, 310 b of afirst link rod 31 a, 31 b; and

two third link rods 33 a, 33 b, and a first end of each third link rod33 a, 33 b is passed through a pivotal axis (not shown in the figure)and pivotally coupled to a second pivotal connecting portion 13 a, 13 bcorresponding to a side panel 11 a, 11 b of the first frame 10, and asecond end is passed through a pivotal axle (not shown in the figure)and pivotally coupled to a corresponding second pivotal connectingportion 311 a, 311 b of a first link rod 31 a, 31 b, wherein theenabling assembly 4 according to a preferred embodiment comprises:

a fixed rod 34, fixed between the two first link rods 31 a, 31 b andextended to a lateral side of a connecting rod 35; and

an actuating device 40, including a motor 41 for supplying a motivepower, and a moving element 42 driven by the motor 41 for movingflexibly, and the moving element 42 is pivotally coupled to theconnecting rod 35 of the fixed rod 34;

such that each set of the corresponding first link rod 31 a, 31 b,second link rod 32 a, 32 b, third link rod 33 a, 33 b, and side panel 11a, 11 b constitutes a structure of four link mechanism (11 a, 31 a, 32a, 33 a/ 11 b, 31 b, 32 b, 33 b).

Since the first link rods 31 a, 31 b can be rotated with respect to thesecond link rod 32 a, 32 b and the third link rod 33 a, 33 b, and thesecond link rod 32 a, 32 b and the third link rod 33 a, 33 b will rotatein opposite directions, and thus the first link rod 31 a, 31 b canrotate with respect to the frame 10, and the second frame 20 is fixedwith the first link rods 31 a, 31 b by an actuating device 40, such thatthe second frame 20 and the elliptical structure 2 also can be rotatedwith respect to the first frame 10 and folded upright. In other words,when the foregoing structure of four link mechanism (11 a, 31 a, 32 a,33 a/ 11 b, 31 b, 32 b, 33 b) operated with the actuating device 40 andthe second frame 20 is secured on a floor, the actuating device 40 isenabled to push or pull the first link rods 31 a, 31 b to rotate withrespect to the second frame 20, and the first link rod 31 a, 31 b, thesecond link rod 32 a, 32 b, and the third link rod 33 a, 33 b areoperated to ascend or descend the front end of the second frame 20, soas to change the inclination of the second frame 20 (as shown in FIGS.1, 8, 9, and 10). Further, when the elliptical fitness machine is not inuse, the free end at the rear of the second frame 20 is lifted upright,so that the second frame 20 can be rotated and folded upright withrespect to the first frame 10 (as shown in FIGS. 1, 6, 7, 11, and 12).

Referring to FIG. 1 for the preferred embodiment of the presentinvention, an output end of the actuating device 40 is a rotate rod 43screwed to the moving element 42, such that when the rotate rod 43 isrotated, the moving element 42 can move on the rotate rod 43.

In FIG. 12, an actuating device 60 is installed and connected betweenthe first frame 10 and the second frame 20 for providing a subsidiaryforce when the second frame 20 is rotated and folded upright withrespect to the first frame 10.

In the elliptical structure on the second frame 20 as shown in FIG. 1,the second frame 20 includes two sliding tracks 25 a, 25 b, and thesecond end of each pedal arm 23 a, 23 b includes a roller 230 a, 230 b,and the second end of each pedal arm 23 a, 23 b is embedded into acorresponding sliding track 25 a, 25 b, such that the roller 230 a, 230b can be rolled on the corresponding sliding track 25 a, 25 b. In afurther preferred embodiment of the present invention, the sliding track25 a, 25 b includes a recessive guide groove 250 a, 250 b separately onboth sides of the sliding track 25 a, 25 b, and the second end of thepedal arm 23 a, 23 b is pivotally coupled to a wheel base 26 a, 26 b,and each wheel base 26 a, 26 b includes a plate 260 a, 260 b extendeddownward from the wheel base 26 a, 26 b, and the internal surface ofeach plate 260 a, 260 b is pivotally coupled to two rollers 230 a, 230b, and the roller 230 a, 230 b of each plate 260 a, 260 b is embeddedinto a corresponding guide groove 250 a, 250 b.

In FIG. 1, the first frame 10 includes a pillar 110 a, 110 b extendedupward from and disposed separately on both sides of the first frame 10,and each pillar 110 a, 110 b includes a handgrip 12 a, 12 b.

In FIG. 1, the first frame 10 includes a pillar 110 a, 110 b extendedupward from and disposed on both sides of the first frame 10, and eachpillar 110 a, 110 b is pivotally to a shaking rod 13 a, 13 b extendedvertically up and down, and each pedal arm 23 a, 23 b of the secondframe 20 is pivotally to the first end of a link rod 14 a, 14 b, and thesecond end of the link rod 14 a, 14 b is coupled to the bottom of acorresponding shaking rod 13 a, 13 b, and the top of each shaking rod 13a, 13 b has a handle 130 a, 130 b. In a further preferred embodiment,the lower half of each shaking rod 13 a, 13 b includes a C-shape crosssection extended along the shaking rod 13 a, 13 b to the first guidegroove 131 a, 131 b, and the second frame 20 includes two correspondinglink rods 14 a, 14 b separately installed in a guide track 15 a, 15 b,and each lateral side of the guide track 15 a, 15 b has a C-shape crosssection extended axially along the first guide track 15 a, 15 b to thesecond guide groove 150 a, 150 b, and each link rod 14 a, 14 b includesa first roller 16 a, 16 b and a second roller 17 a, 17 b separatelydisposed proximate to the ends of the link rod 14 a, 14 b. The firstroller 16 a, 16 b is embedded and limited in the corresponding firstguide groove 131 a, 131 b and rolled in the first guide groove 131 a,131 b, and the second roller 17 a, 17 b is embedded and limited in thecorresponding second guide groove 150 a, 150 b and rolled in the secondguide groove 150 a, 150 b. With such design, the second frame 20 can berotated and folded upright with respect to the first frame 10 to avoidany interference to the shaking rod 13 a, 13 b and the second frame 20.

Referring to FIGS. 1, 13, 14 for a preferred embodiment of the presentinvention, the first frame 10 further comprises a sliding track 50, andthe axis of the sliding track 50 is extended along the direction of thefront and rear ends of the first frame 10, and the sliding track 50 issheathed onto a sliding rod 51, and the sliding rod 51 can be moved andcontracted with respect to the sliding track 50. The sliding rod 51includes a second pivotal connecting portion 510 pivotally coupled to afirst end of a link rod 52, and the second end of the link rod 52 ispivotally coupled to the second frame 20. The sliding rod 51 includes alatch 53 pivotally coupled thereon, and a first end of the latch 53includes a hook portion 530, and a spring 54 is installed between thesecond end of the latch 53 and the sliding rod 51. The first frame 10includes a hooked portion 100 corresponding to the hook portion 530 ofthe latch 53, such that when the second frame 20 is rotated and foldedupright with respect to the first frame 10, the sliding rod 51 iscontracted with respect to the sliding track 50, and the hook portion530 of the latch 53 will be hooked and fixed to the hooked portion 100of the first frame 10, such that the second frame 20 is securely fixedand supported with respect to the first frame 10. If the second frame 20is set down for the use of the elliptical fitness machine, the slidingrod 51 will be linked and extended backward to increase the area of thesupporting plane to give a better stability when a user is doingexercises on the second frame 20.

In FIG. 1, the second frame further includes a flywheel 21 pivotallycoupled thereon, and the flywheel 21 and the rotating member 22 arecoaxially and pivotally coupled to the second frame 20, and the flywheel21 includes a magnetic resisting device 27, such that when the flywheel21 rotates, the magnetic lines of the magnet on the magnetic resistingdevice 27 is cut off, and the flywheel 21 produces a magnetic resistanceto improve the exercise performance.

In FIG. 15, the bottom of the first frame 10 supported on a floorconstitutes a supporting plane. When the second frame 20 with theelliptical structure 2 is folded fully upright with respect to the firstframe 10, the second frame 20 and the elliptical structure 2 have acenter of gravity G falling within the range of the supporting plane ofthe first frame 10.

While the invention has been described by way of example and in terms ofa preferred embodiment, it is to be understood that the invention is notlimited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

1. A foldable elliptical fitness machine, comprising a first frame and a second frame, wherein the first frame securely supported on a floor and the second frame installed an elliptical structure, and the second frame being pivotally coupled to the first frame by a pivoting device, such that the second frame and the elliptical structure can be rotated and folded upright with respect to the first frame, and the first frame supports the second frame, and the elliptical structure comprises a rotating member having two eccentric pivotal points, and two pedal arms, and the middle of the rotating member is pivotally coupled with the second frame, and the two pivotal points of the rotating member are separately and pivotally coupled to a first end of a corresponding pedal arm, and the each pedal arm includes a footrest capable of moving in an elliptic path.
 2. The elliptical fitness machine as claimed in claim 1, wherein the rotating member is coaxially coupled to two cranks to define a rigid body and the axle is pivotally coupled to the second frame.
 3. The elliptical fitness machine as claimed in claim 1, wherein the pivoting device is passed through the second frame and the first frame by a pivotal axle, such that the second frame can be rotated to an angle with respect to the first frame.
 4. The elliptical fitness machine as claimed in claim 1, wherein the pivoting device is passed through the second frame and the first frame by a pivotal axle, such that the second frame can be rotated to an angle with respect to the first frame, and a enabling assembly includes a support rod and an actuating device, the support rod pivotally coupled to the rear end of the second frame, and the actuating device is coupled between the support rod and the second frame, and the actuating device includes a body and a contractible rod, and the contractible rod can be contracted with respect to the body to swing the support rod to an angle.
 5. The elliptical fitness machine as claimed in claim 1, wherein the pivoting device is pivotally coupled to a link rod and a swinging rod at the same pivotal point at the front end of the second frame, and another end of the link rod is pivotally coupled to the first frame, and the swinging rod includes a roller pivotally coupled to a free end of the swinging rod, and the first frame has a track thereon, and the roller of the swinging rod is in contact with the track, and a enabling assembly connected between the swinging rod and the first frame, the enabling assembly includes an actuating device connected between the first frame and the swinging rod, and the actuating device includes a body and a contractible rod, and the contractible rod can be contracted with respect to the body to swing the swinging rod to an angle.
 6. The elliptical fitness machine as claimed in claim 1, wherein the pivoting device comprises: two side panels, disposed at the first frame, the each side panel includes a first pivotal connecting portion and a second pivotal connecting portion; two side rods, disposed at the second frame, and the each side rod includes a pivotal connecting portion disposed proximate to an end of the second frame; two first link rods, each having a first pivotal connecting portion, a second pivotal connecting portion, and a third pivotal connecting portion, and the third pivotal connecting portion on the each first link rod and the pivotal connecting portion corresponding to the rod on the second frame are passed by a pivotal axle for defining a pivotal connection; two second link rod, and a first end of the each second link rod having a pivotal axle and being pivotally coupled to a first pivotal connecting portion corresponding to the side panel of the first frame, and the second end includes a pivotal axle pivotally coupled to a corresponding first pivotal connecting portion of the first link rod; and two third link rods, and a first end of the each third link rod includes a pivotal axle pivotally coupled to a second pivotal connecting portion corresponding to the side panel of the first frame, and a second end includes a pivotal axle pivotally coupled to the second pivotal connecting portion corresponding to the first link rod; and an enabling assembly comprises: a fixed rod, fixed to the two first link rods, and a lateral side of the fixed rod is extended to a connecting rod; and an actuating device, including a motor and a moving element driven by the motor to move and contract, and the moving element is pivotally coupled to the connecting rod of the fixed rod; each set of the first link rod, the second link rod, the third link rod, and the side panel constitutes a structure of four link mechanism, such that when the actuating device drives the moving element, the structure of four link mechanism will move to drive an end of the second frame to ascend to change the inclination of the second frame.
 7. The elliptical fitness machine as claimed in claim 6, wherein the second link rod and the third link rod are rotated in opposite directions with respect to the first frame.
 8. The elliptical fitness machine as claimed in claim 6, wherein the actuating device has an output end being a rotate rod, and the rotate rod is screwed with the moving element, such that when the rotate rod is rotated, the moving element can move on the rotate rod.
 9. The elliptical fitness machine as claimed in claim 6, further comprising an actuating device coupled between the first frame and the second frame for providing a subsidiary force to rotate and fold the second frame upright with respect to the first frame.
 10. The elliptical fitness machine as claimed in claim 1, wherein the second frame includes two sliding tracks, and a second end of the two pedal arms separately have a roller, and a second end of the each pedal arm is embedded into the sliding track, such that the roller can roll on the corresponding sliding track.
 11. The elliptical fitness machine as claimed in claim 10, wherein the sliding track includes a recessive guide groove disposed separately on both sides of the sliding track, and a second end of the pedal arm is pivotally coupled to a wheel base, and the wheel base includes a plate extended down separately from both sides of the wheel base, and the internal surface of the each plate is pivotally coupled to two of the rollers, and the roller of the each plate is embedded in the corresponding guide groove.
 12. The elliptical fitness machine as claimed in claim 1, wherein the first frame includes a pillar extended downward separately from both sides of the first frame, and the each pillar includes a handgrip.
 13. The elliptical fitness machine as claimed in claim 1, wherein the first frame includes a pillar extended upward separately from both sides of the first frame, and the each pillar is pivotally coupled to a shaking rod extended vertically up and down, and the each pedal arm on the second frame is pivotally coupled to a first end of a link rod, and a second end of the each link rod is coupled to the bottom of a corresponding shaking rod, and the each shaking rod includes a handle at the top of the shaking rod.
 14. The elliptical fitness machine as claimed in claim 13, wherein the each shaking rod includes a C-shape cross section disposed at its lower half and a first guide groove extended axially along the shaking rod, and the second frame includes a guide track disposed separately on the two link rods, and the each guide track includes a C-shape cross section at a lateral side of the guide track and a second guide groove extended axially along the guide track, and the each link rod includes a first roller and a second roller disposed separately on the distal ends of the link rod, and the first roller is embedded and limited in the corresponding first guide groove and rolled in the first guide groove, and the second roller is embedded and limited in the corresponding second guide groove and rolled in the second guide groove.
 15. The elliptical fitness machine as claimed in claim 1, wherein the first frame further comprising a sliding track, and the axial line of the sliding track is extended along the direction of the front and rear ends of the first frame, and the sliding track is sheathed onto the sliding rod, such that the sliding rod can move with respect to the sliding track for a contraction, and the sliding rod includes a second pivotal connecting portion, and the second pivotal connecting portion is pivotally coupled to a first end of a link rod, and the link rod second end is pivotally coupled to the second frame, and the sliding rod includes a latch pivotally coupled thereon, and a first end of the latch includes a hook portion, and a spring is installed between a second end of the latch and the sliding rod, and the first frame includes a hooked portion corresponding to the hook portion of the latch, such that when the second frame is rotated and folded upright with respect to the first frame, the sliding rod is contracted with respect to the sliding track, and the hook portion of the latch is hooked and fixed by the hooked portion of the first frame for fixing the second frame with the corresponding first frame.
 16. The elliptical fitness machine as claimed in claim 1, wherein the second frame further comprises a flywheel, and the flywheel and the rotating member are coaxially and pivotally coupled to the second frame, and the flywheel includes a magnetic resisting device, such that when the flywheel is rotated to cut off a magnetic line of a magnet on the magnetic resisting device, the flywheel produces a magnetic resistance.
 17. The elliptical fitness machine as claimed in claim 1, wherein the first frame having a bottom supported on a floor constitutes a supporting plane, such that when the second frame and the elliptical structure are folded fully upright with respect to the first frame, the center of gravity of a structure comprised of the second frame and the elliptical structure falls within the range of the supporting plane. 